Aramid-mica composite insulating nanopaper and preparation method thereof

Abstract

An aramid-mica composite insulating nanopaper and a preparation method thereof are disclosed. A mixture of mica and urea is subjected to a solid-phase ball milling, to obtain nano mica modified with amino groups on the surface, which is then assembled with the aramid nanofiber by stepwise suction filtration according to the present disclosure, to form an ordered nanopaper, thereby obtaining an aramid-mica composite insulating nanopaper with ultra-high insulation performances.

What is claimed is: 
     
       1. A method for preparing an aramid-mica composite insulating nanopaper, comprising,
 ball milling and mixing mica and urea to obtain a ball-milled material; 
 washing the ball-milled material to remove free urea from the ball-milled material to obtain a washed solid; 
 dispersing the washed solid in water to obtain a dispersion; 
 subjecting an aramid nanofiber dispersion to a first vacuum filtration to obtain a solid; 
 adding the dispersion to the solid to obtain a mixture; 
 subjecting the mixture to a second vacuum filtration to obtain a mixed solid; 
 performing in sequence a third vacuum filtration and a fourth vacuum filtration on the mixed solid to obtain a final mixed solid; and 
 drying the final mixed solid to obtain the aramid-mica composite insulating nanopaper. 
 
     
     
       2. The method as claimed in  claim 1 , wherein a mass ratio of mica to urea is in a range of 1:(1-60), and the ball milling is performed for 6 to 100 hours, with a rotation speed of 100-600 rpm. 
     
     
       3. The method as claimed in  claim 1 , wherein the concentration of the mica nanosheet dispersion is in a range of 0.2-1 mg/mL. 
     
     
       4. The method as claimed in  claim 1 , wherein the aramid nanofiber dispersion is prepared by a method comprising:
 mixing an aramid nanofiber-dimethyl sulfoxide dispersion with water; and 
 homogenizing to obtain the aramid nanofiber dispersion. 
 
     
     
       5. The method as claimed in  claim 4 , wherein the concentration of the aramid nanofiber-dimethyl sulfoxide dispersion is 2 mg/mL, and a volume ratio of the aramid nanofiber-dimethyl sulfoxide dispersion to water is in a range of 1:(1-10). 
     
     
       6. The method as claimed in  claim 4 , wherein the homogenizing is performed for 1-10 minutes. 
     
     
       7. The method as claimed in  claim 4 , wherein the concentration of the aramid nanofiber dispersion is in a range of 0.2-1 mg/mL. 
     
     
       8. The method as claimed in  claim 1 , wherein the concentration of the aramid nanofiber dispersion is in a range of 0.2-1 mg/mL. 
     
     
       9. The method as claimed in  claim 1 , wherein a volume ratio of the aramid nanofiber dispersion to the dispersion is in a range of (0-10):(0-10), with the proviso that the volumes of the aramid nanofiber dispersion and the dispersion are not zero.